1. Field of the Invention
This invention relates to the treatment of intrahepatic cholestatic diseases.
2. Description of the Related Art
Intrahepatic Cholestatic Diseases
Cholestasis is a condition in which the flow of bile from the liver to the duodenum is slowed or blocked. Cholestasis may be divided conveniently into two types: intrahepatic cholestasis, inside the liver, where bile formation is disturbed by conditions such as various diseases, extended intravenous nutrition, or as a side effect of certain drugs (such as some antibiotics); and extrahepatic cholestasis, occurring outside the liver, typically where the flow of bile is obstructed by a mechanical partial or complete closure of the bile duct, such as by bile duct tumors, cysts, bile duct stones, strictures, or pressure on the bile duct; though primary sclerosing cholangitis (PSC) may be intrahepatic or extrahepatic. Common symptoms of cholestasis include fatigue, pruritus (itching), jaundice, and xanthoma (deposits of cholesterol-rich material under the skin). The effects of cholestasis are profound and widespread, leading to worsening liver disease with systemic illness, liver failure, and the need for liver transplantation.
Intrahepatic cholestatic diseases include, in order of decreasing frequency, primary biliary cholangitis (formerly known as primary biliary cirrhosis) (PBC), primary sclerosing cholangitis (PSC), progressive familial intrahepatic cholestasis (PFIC), and Alagille syndrome (AS).
PBC is an autoimmune disease of the liver marked by the slow progressive destruction of the small bile ducts of the liver, with the intralobular ducts affected early in the disease. When these ducts are damaged, bile builds up in the liver (cholestasis) and over time damages the tissue, which can lead to scarring, fibrosis and cirrhosis. Recent studies have shown that it may affect up to 1 in 3,000-4,000 people, with a sex ratio at least 9:1 female to male. There is no cure for PBC, and liver transplantation often becomes necessary; but medication such as ursodeoxycholic acid (UDCA, ursodiol) to reduce cholestasis and improve liver function, cholestyramine to absorb bile acids, modafinil for fatigue, and fat-soluble vitamins (vitamins A, D, E, and K, since reduced bile flow makes it difficult for these vitamins to be absorbed) may slow the progression to allow a normal lifespan and quality of life. UDCA is the only drug approved in the United States to treat PBC. Japanese researchers have reported that the addition of bezafibrate, a peroxisome proliferator-activated receptor-α (PPARα) and pregnane X receptor agonist, to UDCA is helpful in treating patients who are refractory to UDCA monotherapy, improving serum biliary enzymes, cholesterol (C), and triglycerides (TGs).
PSC is a chronic cholestatic liver disease characterized by intra- or extrahepatic biliary duct inflammation and fibrosis, eventually leading to cirrhosis. The underlying cause of the inflammation is believed to be autoimmunity; and about three-fourths of patients with PSC have inflammatory bowel disease, usually ulcerative cholitis, though this is reported to vary by country, as is the prevalence (generally reported at about 1 in 10,000) and sex ratio (generally reported as predominately male). Standard treatment includes UDCA, which has been shown to lower elevated liver enzyme numbers in people with PSC, but has not improved liver survival or overall survival; and also includes antipruritics, cholestyramine, fat-soluble vitamins, and antibiotics to treat infections (bacterial cholangitis). In a study reported in 2009, long-term high-dose UDCA therapy was associated with improvement in serum liver tests in PSC but did not improve survival and was associated with higher rates of serious adverse events. Liver transplantation is the only proven long-term treatment.
PFIC refers to a group of three types of autosomal recessive disorders of childhood associated with intrahepatic cholestasis: deficiency of familial intrahepatic cholestasis 1 (PFIC-1), deficiency of bile salt export pump (PFIC-2), and deficiency of multidrug resistance protein 3 (PFIC-3). They have a combined incidence of 1 in 50,000-100,000. The onset of the disease is usually before age 2, with PFIC-3 usually appearing earliest, but patients have been diagnosed with PFIC even into adolescence. Patients usually show cholestasis, jaundice, and failure to thrive; and intense pruritus is characteristic. Fat malabsorption and fat soluble vitamin deficiency may appear. Biochemical markers include a normal γ-glutamyl transpeptidase (GGT) in PFIC-1 and PFIC-2, but a markedly elevated GGT in PFIC-3; while serum bile acid levels are greatly elevated; though serum cholesterol levels are typically not elevated, as is seen usually in cholestasis, because the disease is due to a transporter as opposed to an anatomical problem with biliary cells. The disease is typically progressive without liver transplantation, leading to liver failure and death in childhood; and hepatocellular carcinoma may develop in PFIC-2 at a very early age. Medication with UDCA is common; supplemented by fat-soluble vitamins, cholestyramine, and pancreatic enzymes in PFIC-1.
AS, also known as Alagille-Watson syndrome, syndromic bile duct paucity, and arteriohepatic dysplasia, is an autosomal dominant disorder associated with liver, heart, eye and skeletal abnormalities, as well as characteristic facial features; with an incidence of about 1 in 100,000. The liver abnormalities are narrowed and malformed bile ducts within the liver; and these result in obstruction of bile flow, causing cirrhosis (scarring) of the liver. AS is predominately caused by changes in the Jagged1 gene, located on chromosome 20. In 3-5% of cases, the entire gene is deleted (missing) from one copy of chromosome 20; in the remainder, there are changes or mutations in the Jagged1 DNA sequence. In a very small number of cases, less than 1 percent, changes in another gene, Notch2, result in AS. In about one-third of the cases, the mutation is inherited; in about two-thirds, the mutation is new in that case. There is no cure for AS, though the severity of liver disease typically peaks by 3 to 5 years of age and often resolves by 7 to 8 years of age. In some people, the hepatic disease will progress to end-stage liver disease and may require liver transplantation; approximately 15% of patients with AS require liver transplantation. A number of different medications, for example UDCA, have been used to improve bile flow and reduce itching, and many patients are given high doses of fat-soluble vitamins.
Alkaline phosphatase (ALP) and GGT are key markers of cholestasis. While an elevation of one of them alone does not indicate cholestasis, and other parameters would be needed for confirmation, elevation in both ALP and GGT is indicative of cholestasis; and a decrease in both indicates improvement of cholestasis. Thus ALP and GGT levels serve as biochemical markers for the presence of biliary pathophysiology present in intrahepatic cholestatic diseases, and ALP level has been used as a primary outcome marker in clinical studies of intrahepatic diseases such as PBC.
Treatments for Intrahepatic Cholestatic Diseases
As mentioned above, UDCA is a common treatment for intrahepatic cholestatic diseases, because of its action in reducing cholestasis and improving liver function. However, a Cochrane Review of UDCA in PBC in 2012 found that, although UDCA showed a reduction in biomarkers of liver pathology, jaundice, and ascites, there was no evidence in the medical literature for any benefit of UDCA on mortality or liver transplantation, while its use was associated with weight gain and costs.
Obeticholic acid (6α-ethylchenodeoxycholic acid), a semi-synthetic bile acid analog that is a highly potent farnesoid X receptor agonist, has completed a Phase 2 study in combination with ursodeoxycholic acid for PBC, and is under study in a second Phase 2 study alone on lipoprotein metabolism in PBC and a Phase 3 placebo-controlled study in PBC. However, the only long-term treatment for many patients with intrahepatic cholestatic diseases is liver transplantation.
It would be desirable to develop pharmacological treatments for intrahepatic cholestatic diseases.
MBX-8025
MBX-8025 is the compound of the formula

MBX-8025 has the chemical name (R)-2-(4-((2-ethoxy-3-(4-(trifluoromethyl)phenoxy)propyl)thio)-2-methylphenoxy)acetic acid [IUPAC name as generated by CHEMDRAW ULTRA 12.0]. MBX-8025 and its synthesis, formulation, and use is disclosed in, for example, U.S. Pat. No. 7,301,050 (compound 15 in Table 1, Example M, claim 49), U.S. Pat. No. 7,635,718 (compound 15 in Table 1, Example M), and U.S. Pat. No. 8,106,095 (compound 15 in Table 1, Example M, claim 14). Lysine (L-lysine) salts of MBX-8025 and related compounds are disclosed in U.S. Pat. No. 7,709,682 (MBX-8025 L-lysine salt throughout the Examples, crystalline forms claimed).
MBX-8025 is an orally active, potent (2 nM) agonist of peroxisome proliferator-activated receptor-δ (PPARδ), It is specific (>600-fold and >2500-fold compared with PPARα and peroxisome proliferator-activated receptor-γ receptors). PPARδ activation stimulates fatty acid oxidation and utilization, improves plasma lipid and lipoprotein metabolism, glucose utilization, and mitochondrial respiration, and preserves stem cell homeostasis. According to U.S. Pat. No. 7,301,050, PPARδ agonists, such as MBX-8025, are suggested to treat PPARδ-mediated conditions, including “diabetes, cardiovascular diseases, Metabolic X syndrome, hypercholesterolemia, hypo-high density lipoprotein (HDL)-cholesterolemia, hyper-low density protein (LDL)-cholesterolemia, dyslipidemia, atherosclerosis, and obesity”, with dyslipidemia said to include hypertriglyceridemia and mixed hyperlipidemia.
A Phase 2 study of MBX-8025 L-lysine dihydrate salt in mixed dyslipidemia (6 groups, 30 subjects/group: once daily placebo, atorvastatin (ATV) 20 mg, or MBX-8025 L-lysine dihydrate salt at 50 or 100 mg (calculated as the free acid) capsules alone or combined with ATV 20 mg, for 8 weeks) has been reported by Bays et al., “MBX-8025, A Novel Peroxisome Proliferator Receptor-δ Agonist: Lipid and Other Metabolic Effects in Dyslipidemic Overweight Patients Treated with and without Atorvastatin”, J. Clin. Endocrin. Metab., 96(9), 2889-2897 (2011) and Choi et al., “Effects of the PPAR-δ agonist MBX-8025 on atherogenic dyslipidemia”, Atherosclerosis, 220, 470-476 (2012). Compared to placebo, MBX-8025 alone and in combination with ATV significantly (P<0.05) reduced apolipoprotein B-100 by 20-38%, LDL by 18-43%, triglycerides (TGs) by 26-30%, non-HDL-C by 18-41%, free fatty acids by 16-28%, and high-sensitivity C-reactive protein by 43-72%; it raised HDL-C by 1-12% and also reduced the number of patients with the metabolic syndrome and a preponderance of small LDL particles. MBX-8025 reduced small/very small LDL particles by 40-48% compared with a 25% decrease with ATV; and MBX-8025 increased large LDL particles by 34-44% compared with a 30% decrease with ATV. MBX-8025 significantly reduced ALP by 32-43%, compared to reductions of only 4% in the control group and 6% in the ATV group; and significantly reduced GGT by 24-28%, compared to a reduction of only 3% in the control group and an increase of 2% in the ATV group. Thus MBX-8025 corrects all three lipid abnormalities in mixed dyslipidemia—lowers TGs and LDL and raises HDL, selectively depletes small dense LDL particles (92%), reduces cardiovascular inflammation, and improves other metabolic parameters including reducing serum aminotransferases, increases insulin sensitivity (lowers homeostatic model assessment-insulin resistance, fasting plasma glucose, and insulin), lowers GGT and ALP, significantly (>2-fold) reduces the percentage of subjects meeting the criteria for metabolic syndrome, and trends towards a decrease in waist circumference and increase in lean body mass. MBX-8025 was safe and generally well-tolerated, and also reduced liver enzyme levels. As explained in US Patent Application Publication No. 2010-0152295, MBX-8025 converts LDL particle size pattern I (a predominant LDL particle size of from 25.75 nm to 26.34 nm) to pattern A (a predominant LDL particle size of greater than 26.34 nm); and from pattern B (a predominant LDL particle size of less than 25.75 nm) to pattern I or A, where the LDL particle size is measured by gradient-gel electrophoresis.
The disclosures of the documents referred to in this application are incorporated into this application by reference.